Mid-IR Surface Plasmon Polaritons in CdZnO thin films on GaAs

Metal-oxides are known to be ideal alternatives to noble metals for mid-IR plasmonics, but they are typically grown on substrates as sapphire or glass, which cannot be used as active materials in electronic devices. We demonstrate here that thin Cd(Zn)O films can be integrated on GaAs, one of the dominant optoelectronic material platforms in the mid-IR. Cd(Zn)O is likely the best plasmonic material in this region of the spectrum, and we show that when deposited on GaAs it yields polycrystalline films that support surface plasmon polaritons (SPPs). As a result of the preserved out-of-plane orientation of the crystal grains, the plasma damping in these layers is very moderately degraded with respect to monocrystalline layers on sapphire, yielding an SPP quality factor comparable to other typical TCOs like AZO, GZO or ITO, but with the added functionality of being integrated on GaAs. Hence, these results open the door for the development of future hybrid Cd(Zn)O/GaAs technology, where Cd(Zn)O can be used to amplify the electric field in underlying devices, e.g. photodetectors.